findAllByString 함수의 조건문 설정이 잘 이해가 안되요

public List<Order> findAllByString(OrderSearch orderSearch) {

    String jpql = "select o from Order o join o.member m";
    boolean isFirstCondition = true;

    //주문 상태 검색
    if (orderSearch.getOrderStatus() != null) {
        if (isFirstCondition) {
            jpql += " where";
            isFirstCondition = false;
        } else {
            jpql += " and";
        }
        jpql += " o.status = :status";
    }

    //회원 이름 검색
    if (StringUtils.hasText(orderSearch.getMemberName())) {
        if (isFirstCondition) {
            jpql += " where";
            isFirstCondition = false;
        } else {
            jpql += " and";
        }
        jpql += " m.name like :name";
    }

    TypedQuery<Order> query = em.createQuery(jpql, Order.class)
            .setMaxResults(1000);

    if (orderSearch.getOrderStatus() != null) {
        query = query.setParameter("status", orderSearch.getOrderStatus());
    }
    if (StringUtils.hasText(orderSearch.getMemberName())) {
        query = query.setParameter("name", orderSearch.getMemberName());
    }

    return query.getResultList();
}

질문:

위에서 isFirstCondition이 true 가 아니면 and 를 붙이는게 잘 이해가 안되요 
where 도 없는 상태에서 and를 붙이는건가요?

code)

    if (orderSearch.getOrderStatus() != null) {
        if (isFirstCondition) {
            jpql += " where";
            isFirstCondition = false;
        } else {
            jpql += " and";
        }
        jpql += " o.status = :status";
    }

https://okky.kr/articles/1347075

//주문 상태 검색
if (orderSearch.getOrderStatus() != null) {
    if (isFirstCondition) {
        jpql += " where";
        isFirstCondition = false;
    } else {
        jpql += " and";
    }
    jpql += " o.status = :status";
}